Measurement of Particulate Carbon in Atmospheric Aerosol in Helsinki

By means of a simple optical apparatus the levels and variations of concentrations of elemental carbon in particles were measured. Additionally, relations between variations of elemental carbon, lead, sulfate, total suspended particle, and nitrate concentrations were studied. Calibration was performed on real samples analyzed by a wet chemical method.     

Geo-referencing of continental-scale JERS-1 SAR mosaics based on matching homologous features with a digital elevation model: theory and practice

An effective method for a posteriori ortho-rectification of continental-scale synthetic aperture radar (SAR) mosaics using a digital elevation model (DEM) has been developed. The method is based on homologous feature matching between the DEM and a simulated SAR image. The simulated image is derived from the radar-viewing geometry, topographic information and contextual information provided by the Shuttle Radar Topography Mission (SRTM), shorelines and water bodies database (SWBD) and GeoCover Landsat mosaics. Two large L-band SAR mosaics (the global boreal forest mapping (GBFM) Siberia mosaic and the global rain forest mapping (GRFM) Africa mosaic), assembled from the Japanese Earth Resources Satellite-1 (JERS-1) data, were accurately geo-referenced and ortho-rectified. The GRFM Africa mosaic was also radiometrically corrected for topographic effects. The accurate co-registration with the DEM allows for improved classification methods based on the combination of SAR backscatter with terrain features. Comparison of the revised GBFM and GRFM mosaics with a forthcoming set of continental-scale mosaics assembled from the Advanced Land Observing Satellite (ALOS) Phased Array L-band Synthetic Aperture Radar (PALSAR) data will offer a unique possibility for change detection studies over the Tropical and Boreal forest zones with a temporal spacing of some 10 years.     

Adhesion, spreading and osteogenic differentiation of mesenchymal stem cells cultured on micropatterned amorphous diamond, titanium, tantalum and chromium coatings on silicon

It was hypothesized that human mesenchymal stromal cell (hMSC) can be guided by patterned and plain amorphous diamond (AD), titanium (Ti), tantalum (Ta) and chromium (Cr) coatings, produced on silicon wafer using physical vapour deposition and photolithography. At 7.5 h hMSCs density was 3.0–3.5× higher (P < 0.0003, except Ti) and cells were smaller (68 vs. 102 μm, P 0.000006–0.02) on patterns than on silicon background. HMSC-covered surface of the background silicon was lower on Ti than AD patterns (P = 0.015), but at 5 days this had reversed (P = 0.006). At 7.5 h focal vinculin adhesions and actin cytoskeleton were outgoing from pattern edges so cells assumed geometric square shapes. Patterns allowed induced osteogenesis, but less effectively than plain surfaces, except for AD, which could be used to avoid osseointegration. All these biomaterial patterns exert direct early, intermediate and late guidance on hMSCs and osteogenic differentiation, but indirect interactions exist with cells on silicon background.     

Deterministic and statistical properties of two-dimensional FIR-median hybrid filters

In this paper, we present a new class of two-dimensional FIR-median hybrid (FMH) filters, which we call separable FMH filters, for image noise smoothing. In a separable FMH filter, a one-dimensional FMH filter is applied to the rows and the columns of an image successively. The deterministic properties of separable and cross window FMH filters are discussed. Under certain assumptions, it is proved that a root of a separable FMH filter is a root of the corresponding cross window FMH filter. The noise attenuating properties of a separable FMH filter are studied and compared with those of the separable median filter, the two-dimensional median filter with a square window, and the cross window FMH filter.     

Characterization of Physical and Mechanical Properties of Miscible Lactose‐Sugars Systems

Lactose‐sugars systems were produced by spray drying. They were lactose, lactose–glucose (4:1) mixtures, lactose–maltose (4:1) mixtures, lactose–sucrose (4:1) mixtures, lactose–trehalose (4:1) mixtures, and lactose–corn syrup solids (CSS) (4:1) mixtures. The physical characteristics, water sorption behavior, glass transition, and mechanical properties of miscible lactose‐sugars systems were investigated. Lactose–glucose mixtures had larger particle size than other lactose‐sugars systems after spray drying. The presence of glucose or sucrose in lactose‐sugars mixtures decreased the glass transition temperatures of amorphous systems, while the presence of maltose and trehalose had only minor impact on the glass transition temperatures. Moreover, glucose accelerated the crystallization of amorphous system at 0.44 a_w, but its presence delayed the loss of sorbed water at higher water activities (≥0.54 a_w). Mechanical property study indicated that glucose and sucrose in amorphous system could result in an increase of molecular mobility, while the presence of CSS could decrease the free volume and maintain the stiffness of the miscible systems.     

A mathematical model for the transmission of Salmonella Typhimurium within a grower-finisher pig herd in Great Britain

In a study of pigs slaughtered at British abattoirs, approximately 23% carried Salmonella in their cecal (large intestine) contents. The most frequent serotype was Salmonella Typhimurium (STM), which was the second most common cause of human salmonellosis in Great Britain. A pig industry-monitoring program was developed to reduce Salmonella infection on British farms. The control of STM infection on the farm requires an understanding of STM transmission dynamics within the herd, and a mathematical model has been developed for an infected grower-finisher farm. The model estimates the probability of a random pig being infected with STM. There are three broad categories of STM infection in pigs: pigs that are infected but unable to transmit the infection (latent); pigs that are infectious, i.e., able to transmit the infection (shedders); and pigs that have stopped shedding but harbor STM in their internal organs (carriers). The model estimates that 21.0% (5th and 95th percentiles, 0.05 to 77.5%) of slaughter-age pigs on an infected farm are likely to be shedding STM. Although this range is wide, it is biologically plausible. Sensitivity analysis of the total number of infected pigs revealed that the most significant input parameters are the probability of effective contact between a specific infectious and susceptible pig and the duration of shedding. The model predicted that 11.5% of pigs would be shedding STM at slaughter age. This value is close to the estimate obtained from a British abattoir survey that 11. 1% of pigs carried STM in their ceca, indicating that the model has reasonable validity.     

Mathematical model of Listeria monocytogenes cross-contamination in a fish processing plant

Listeriosis is a foodborne disease caused by the bacterium Listeria monocytogenes. The food industry and government agencies devote considerable resources to reducing contamination of ready-to-eat foods with L. monocytogenes. Because inactivation treatments can effectively eliminate L. monocytogenes present on raw materials, postprocessing cross-contamination from the processing plant environment appears to be responsible for most L. monocytogenes food contamination events. An improved understanding of cross-contamination pathways is critical to preventing L. monocytogenes contamination. Therefore, a plant-specific mathematical model of L. monocytogenes cross-contamination was developed, which described the transmission of L. monocytogenes contamination among food, food contact surfaces, employees' gloves, and the environment. A smoked fish processing plant was used as a model system. The model estimated that 10.7% (5th and 95th percentile, 0.05% and 22.3%, respectively) of food products in a lot are likely to be contaminated with L. monocytogenes. Sensitivity analysis identified the most significant input parameters as the frequency with which employees' gloves contact food and food contact surfaces, and the frequency of changing gloves. Scenario analysis indicated that the greatest reduction of the within-lot prevalence of contaminated food products can be achieved if the raw material entering the plant is free of contamination. Zero contamination of food products in a lot was possible but rare. This model could be used in a risk assessment to quantify the potential public health benefits of in-plant control strategies to reduce cross-contamination.     

Glass transition and water plasticization effects on crispness of a snack food extrudate

Abstract

A crispy snack model, composed of maltodextrin, wheat flour, salt, and water, with a clearly measurable glass transition was designed and produced by extrusion. The material was used to investigate effects of glass transition and water plasticization on mechanical properties and sensory crispness. Water sorption and the glass transition temperature range were determined gravimetrically and using differential scanning calorimetry (DSC) for samples stored at 0 to 85% relative humidity (RH), respectively. Mechanical properties were determined for extradates rehumidified at 0 to 76% RH. Three sensory panels evaluated crispness intensities of extrudates rehumidified at 33 to 76% RH by either breaking samples with fingers (Finger Task), biting using the incisor teeth (Bite Task), or biting and chewing (Bite‐and‐Chew Task). The extrudate was plasticized by water, as observed from a typical decrease of Tg with increasing water content. Changes in mechanical properties and loss of crispness occurred at an intermediate water activity level coinciding with the extent of plasticization depressing the Tg to below ambient temperature. The changes in mechanical properties and sensory crispness intensities with increasing water activity had sigmoid shapes following the Fermi's model. Loss of crispness as a result of water plasticization is likely to apply to a number of low‐moisture food materials, although various mechanical and sensory properties do not necessarily change in unison as the materials undergo a glass transition.     

Characterization of carbohydrate-protein matrices for nutrient delivery

Amorphous carbohydrates may show glass transition and crystallization as a result of thermal or water plasticization. Proteins often affect the state transitions of carbohydrates in carbohydrate-protein systems. Water sorption behavior and effects of water on glass transition and crystallization in freeze-dried lactose, trehalose, lactose-casein (3: 1), lactose-soy protein isolate (3:1), trehalose-casein (3:1), and trehalose-soy protein isolate (3:1) systems were studied. Water sorption was determined gravimetrically as a function of time, and Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were fitted to the experimental data. Glass transition temperature (T(g)) and instant crystallization temperature (T(ic)) in anhydrous and water plasticized systems were measured using differential scanning calorimetry (DSC). The Gordon-Taylor equation was used to model water content dependence of the T(g) values. The critical water content and water activity (a(w)) at 24 °C were calculated and crystallization of lactose and trehalose in the systems was followed at and above 0.54 a(w). Carbohydrate-protein systems showed higher amounts of sorbed water and less rapid sugar crystallization than pure sugars. A greater sugar crystallization delay was found in carbohydrate-casein systems than in carbohydrate-soy protein isolate systems. The T(g) and T(ic) values decreased with increasing water content and a(w). However, higher T(ic) values for lactose-protein systems were found than for lactose at the same a(w). Trehalose showed lower T(ic) value than lactose at 0.44 a(w) but no instant crystallization was measured below 0.44 a(w). State diagrams for each system are useful in selecting processing parameters and storage conditions in nutrient delivery applications.